Engine components may degrade during operation in various ways. For example, the effectiveness of piston rings in sealing the piston in the combustion chamber may degrade causing increased blow-by of combustion gasses into the engine's crankcase.
One approach to detect engine degradation is to monitor a steady-state crankcase pressure. Diagnostic routines can monitor whether the crankcase pressure rises above a threshold pressure, and generate diagnostic codes or other indications requesting service, de-rating engine power, or shutting down the engine.
However, the inventors herein have recognized that an increase in the steady-state crankcase pressure may be caused by a number of different degraded components and it may be time consuming for a maintenance crew to determine the source of the degraded component during service of the engine, and whether the increased piston blow-by is indeed the source of the degradation.